.panel{
    padding-bottom: 40%;
    position: relative;
}

.wrapper_box{
    position: absolute;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
}

.table{
    width: 100%;
    height: 100%;
    display: table;
}

.table_cell{
    display: table-cell;
    text-align: center;
    vertical-align: middle;
}

.panel-body{
    width: 50%;
    margin: 0 auto;
}

.img_box{
    width: 300px;
    height: 300px;
    margin: 0 auto;
    background-image: url("/upload/images/bg.png");
    background-size: contain;
    background-repeat: no-repeat;
    background-position: center;
    background-color: #FFF;
    border: 1px solid #ddd;
    cursor: pointer;
}

.img_box input{
    width: 100%;
    height: 100%;
    opacity: 0;
}